This invention relates generally to the mounting of electronic equipment, and more particularly to an apparatus for facilitating the extraction of modules from a shelving system.
Amongst the generalized inner-workings of multifaceted apparatus, electronic equipment can be said to have significant value. The architecture of such equipment often entails significant production cost, and electronic equipment often performs vital processing functions producing direct or indirect results in response to data input or operator commands. Thus, any damage done to electronic equipment may be relatively costly, and any malfunction in electronic equipment may lead to incorrect results or greater mechanical and/or electrical failures. The architecture of electronic equipment is usually inherently delicate. Thus, protecting such equipment is important for several reasons. In particular, it is desirable that a housing apparatus, cabinet, or shelving system for receiving and retaining electronic modules: (1) protect the electronic equipment and (2) provide precise alignment of the electronic interfaces (e.g. male and female connectors). Under certain conditions, these basic criteria may be more difficult to meet. Electronic equipment undergoing transport, for instance, experiences an increased risk of damage due to constant subjection to vibrations and other aberrant forces. This is also true for electronic systems of the type employed in aircraft since such electronic systems frequently experience forces that threaten to dislodge and damage them.
To provide better protection of electronic equipment and maintain proper couplings between interfaces, hold-down mechanisms have been introduced. Early hold-down mechanisms secured electronic units onto a rack through the application of a constant pressure. Such hold-down mechanisms effectively protected electronic units from damage and consequently became commonly employed in aircraft electronic shelving systems. However, the design of these hold-down mechanism suffered from several shortcomings. For example, such mechanisms increased the weight of the electronic units. Additionally, early hold-down mechanisms were capable of generating forces greater than necessary potentially damaging the equipment. Several other limitations were also inherent in the architecture of these hold-down mechanisms such as the lack of means to prevent loosening of set-screws and the like during flight.
A more desirable hold-down apparatus is shown and described in U.S. Pat. No. 3,640,141 issued to Hollinsead et al. on Feb. 8, 1972, the teachings of which are herby incorporated by reference. This device, referred to as an extractor hold-down apparatus, is improved over the previous hold-down device in several ways, For example, a singular extractor hold-down apparatus provides sufficient force to suitably secure an electronic unit in place thus reducing the undesirable accumulation of weight. Furthermore, unlike the initial hold-down mechanisms, this extractor hold-down apparatus does not generate excessive forces and provides a convenient way to gauge the applied force. The device is capable of generating a forward driving force for inserting an electronic module to provide proper connection between the module and backplane connectors and an extraction force for dislodging the module from its connections and extracting it (e.g. an extraction force of 100 pounds would not be uncommon). This extractor hold-down device became commonly used in the field of avionics and is now required by the Air Transport Avionics Equipment Interface, ARINC Specifications 600.
Unfortunately, an undesirable upward-directed force is produced by the above described hold-down apparatus during extraction. That is, due to its design, the spindle or axis of the device forms an angle with the plane of the engaging male and female connecters which may be as high as 9 to 25 degrees. Thus, the extraction force is not limited to a desired axis but includes a component which acts perpendicularly to the axis of the connector pins of the male/female connector interface (hereinafter referred to as the axis of the connector interface). In the case of heavier electronic units, this aberrant force is compensated for by the mass of the unit and is not a significant issue. However, lighter electronic units are increasingly being developed and introduced. Unfortunately, the perpendicular force generated by the hold-down extractor apparatus on such lighter units becomes problematic. Specifically, the extraction force generated perpendicular to the desired axis of the connector interface is sufficient to bend the connector pins damaging the module and may perhaps cause the module to wedge preventing further removal. It should also be noted that undesirable forces of this nature may be exacerbated via other sources; for example, by lifting upwards on a handle of a module being removed instead of extracting the module along the line of the connector interface axis.
In view of the foregoing, it should be appreciated that it would be desirable to provide a lightweight, module-extracting apparatus which avoids the generation of forces perpendicular to the axis of the electronic interface. Such a device would be especially suited for use in an avionics shelving apparatus. Additional desirable features will become apparent to one skilled in the art from the foregoing background of the invention and following detailed description of a preferred exemplary embodiment and appended claims.
According with a first aspect of the invention, there is provided an equipment rack including a shelf and a backplane which supports and receives an electronic module having a rear connector. The backplane includes a complementary connector for engaging the rear connector along an insertion axis. An extraction tool is coupled to the shelf and to the module for disengaging the rear connector from the complementary connector while producing an extraction force having a first component substantially along the insertion axis and a second component substantially perpendicular to the insertion axis. A hold-down bracket is coupled to the module and slidably engages the shelf to counteract the second component of the extraction force until the rear connector disengages from the complementary connector.
In accordance with a further aspect of the invention, there is provided an electronic module capable of being supported on a shelf and comprising a housing having at least a front surface, a rear surface, and a bottom surface, the bottom surface for slidably engaging the shelf. The module includes at least a first connector in the rear surface thereof, and a hold-down bracket is fixedly coupled to the bottom surface and cooperates therewith to form a channel capable of slidably engaging at least a portion of the shelf.
According to a still further aspect of the invention, there is provided a hold-down bracket for forming a receiving channel with an undersurface of an electronic module which slidably engages a portion of a shelf. The bracket comprises a cross member having an upper surface and a lower surface, the lower surface for fixedly engaging the undersurface of the module. At least one longitudinal member extends from the cross member and is spaced from the undersurface to form the receiving channel.